[time-nuts] HP and other equipment failure

[Didier Juges]

"audiophile outlets"

You've got to be kidding but not even.

At least, nobody is forcing anybody to buy them...

Didier

Peter Gottlieb <nerd at verizon.net> wrote:

>The current distortion from simple transformer-rectifier-capacitor
>power 
>supplies contains a lot of third harmonic content.  In a 3 phase system
>(as are 
>all distribution systems for commercial and industrial) the third
>harmonic ADDS 
>in the neutral, or creates circulating currents in a delta
>configuration.  These 
>currents, as you mention, can get very large and were the cause of many
>
>transformer explosions in cities as these power supplies became common.
> The 
>transformer designs had to be improved, but the PFC supplies make a big
>difference.
>
>How many of you have looked at the power line waveform, especially in
>an 
>industrial or commercial area?  Doesn't look much like a sine wave,
>does it?  So 
>it's pretty funny to see audiophile outlets 
>(http://www.dedicatedaudio.com/power_outlets).
>
>Peter
>
>
>
>
>On 6/15/2013 6:56 PM, stan, W1LE wrote:
>> PFC to me is power factor correction, not only the classical power
>factor to 
>> minimize (VAR) volt-amp reactive component,
>>  but also to remove the harmonic load  current imposd on the
>electrical power 
>> system.
>> A '90's onward technique. in th 80's and 90's without the harmonic
>load 
>> current reduction and having
>>  a few 100 end items of equipment, each withtheir own  a switch mode
>power 
>> supplly,
>>  it was not uncommon to find hundreds of amps of the third harmonc on
>neutra,
>>   in the electrical power distribution system.
>>
>> Could be a serious EMC problem if you were dealing with voice grade
>channels.
>> And people safety issues.
>>
>> Stan, W1LE   Cape Cod
>>
>>
>>
>> On 15-Jun-13 5:52 PM, J. L. Trantham wrote:
>>> Sorry for the interruption but what is 'PFC'?
>>>
>>> Thanks.
>>>
>>> Joe
>>>
>>> -----Original Message-----
>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]
>On
>>> Behalf Of Poul-Henning Kamp
>>> Sent: Saturday, June 15, 2013 4:09 PM
>>> To: Robert Atkinson; Discussion of precise time and frequency
>measurement
>>> Cc: Perry Sandeen
>>> Subject: Re: [time-nuts] HP and other equipment failure
>>>
>>> In message
><1371329221.83869.YahooMailNeo at web171902.mail.ir2.yahoo.com>,
>>> Robert  Atkinson writes:
>>>
>>>> While I agree with everything else you say, you CAN have too much
>>>> filter capacitance. At least where dc rectifier / filter
>(smoothing)
>>>> circuits are concerned. Increasing C causes increased ripple
>current
>>>> [...]
>>> And ripple current can be a major source of power-line frequency
>noise in
>>> all electronics.
>>>
>>> The main reason why switchmode power-supplies today (can) outperform
>linear
>>> power supplies with respect to noise, is because the legally
>mandated PFC
>>> correction eliminates the bridge-rectifier ripple harmonics.
>>>
>>> I would not hessitate to use a good quality switchmode to replace
>the linear
>>> supply in a HP5370B.
>>>
>>> I did some experiments a couple of years ago, with an
>audio-amplifier:
>>> I put a standard PFC corrector chip on the secondary side of the
>trafo.
>>>
>>> The overall result was not satisfactory, but the 50 Hz "sneer"
>>> we all know and hate was absent, and the "Tzoing!!!!!" power-on
>mechanical
>>> shock from the trafo was also eliminated, as was the consequent
>dimming of
>>> the lights ;-)
>>>
>>> The main reason not to do this, is that you need some physically
>gargantuan
>>> coils for a 10A+ PFC-switcher.
>>>
>>>
>>
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